外文翻译全球移动通信系统概要.docVIP

夜柿馅一瓦肪光鹱乱忏Overview of the Global System for Mobile Communications鏖珙轹悃佼缧吮扛橡朝1 History of GSM琼傻雀氆跷县芨菅哩孽 During the early 1980s, analog cellular telephone systems were experiencing rapid growth in Europe, particularly in Scandinavia and the United Kingdom, but also in France and Germany. Each country developed its own system, which was incompatible with everyone else’s in equipment and operation. This was an undesirable situation, because not only was the mobile equipment limited to operation within national boundaries, which in a unified Europe were increasingly unimportant, but there was also a very limited market for each type of equipment, so economies of scale and the subsequent savings could not be realized.尻丈号仳以杵刑盆踞胚 The Europeans realized this early on, and in 1982 the Conference of Europeans Posts and Telegraphs (CEPT) formed a study group called the Group Special Mobile (GSM) to study and develop a pan-European public land mobile system. The proposed system has to meet certain criteria:色叮胖迁煽霜鞒吧阔噱 ·Good subjective speech quality斤呦晶飓钯缴盏悱汞侯 Low terminal and service cost榇祛猸车驭畋锓聊恩谷 Support for international roaming绀肉条谫溱榆伏州溲枳 Ability to support handheld terminals轰呋历呒慵佶意嗣煌寒 Support for range of new services and facilities灾悭穑奚笱虐际皆砌诩 Spectral efficiency噔妮堞役玑熏还糠六筮 ISDN compatibility瘭梵仿潢琴揉汪毋补阚 In 1989, GSM responsibility was transferred to the European Telecommunication Standards Institute (ETSI), and phase I of the GSM specifications were published in 1990. Commercial service was started in mid-1991, and by 1993 there were 36 GSM networks in 22 countries. Although standardized in Europe, GSM is not only a European standard. Over 200 GSM networks are operational in 110 countries around the world. In the beginning of 1994, there were 1.3 million subscribers worldwide, which had grown to more than 55 million by October 1997. With North America making a delayed entry into the GSM field with a derivative of GSM called PCS1900, GSM systems exist on every continent, and the a